Numerical investigation of the effect of nozzle geometry of diesel injector and needle lift on spray formation

The fuel spray analysis in the combustion chamber, as a significant parameter in optimizing nozzle performance, is associated with complexity, both numerical and experimental, due to the high pressure and speed of the fuel flow. In this paper, the simulation of the effect of nozzle geometry and the needle lift on the Diesel fuel spray has been done by usage of Fluent software. The spray penetration length is considered as a major criterion for improving the performance of the Diesel engine. The size and location of cavitation phenomena within the nozzle will change with the deformation of the nozzle geometry and the needle lift, under constant conditions. Accordingly, firstly the effect of nozzle geometry and needle lift on the formation of cavitation in the Diesel nozzle was simulated transiently with moving mesh and using the scanner-Saur method. Then, using the obtained results, fuel spray was simulated by SSD method. In this paper, the aim of increasing the accuracy of problem solving is investigated for laboratory and experimental values. The process of flow changes in the nozzle is solved unsteady, and then the outlet results at the upstream are used as input values for flow downstream and spray. This article shows that how the penetration length of spray will change with the deformation of the nozzle geometry and needle lift.